Silver halide photographic materials are not only demanded to have high sensitivity but also be less changeable in the photographic capability during storage after the preparation of the photographic material and also less changeable in the photographic capability after photographing until development processing.
Out of changes in the photographic capability after photographing until development processing, with respect to the prevention of latensification, JP-A-59-162546 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a method of using a hardening agent having an active vinyl group in combination with a triazine-base compound.
However, the above-described method is insufficient in the prevention effect and a further improvement has been demanded.
On the other hand, full color photographic materials use a plurality of emulsions different in the spectral sensitivity as a superposed layer structure, thereby achieving the object of full color photograph. The emulsions used therein have been fairly improved, however, they are still unsatisfactory because fogging of the latent image or intensification/regression is caused. In order to improve storability of the emulsion, for example, 2-hydroxamino-1,3,5-triazines are effective. However, the layers are different in the storability from each other depending upon the emulsion used therein. Accordingly, in recent years, it is being rather strongly demanded to improve storability of a latent image of a specific emulsion layer.
Many of known 2-hydroxylamine-1,3,5-triazines diffuse and act on the emulsion in the layer other than the objective layer and as a result, the balance in the gradation among respective layers is lost. Further, hydroxamic acids having a specific structure described in U.S. Pat. Nos. 4,339,515 and 4,330,606, JP-A-59-198453 and JP-A-3-293666 are used to improve storability of a color image or as a nucleophilic agent and different from the present invention in the use object. Moreover, the above-described hydroxamic acids are insufficient in causing action only on an emulsion in a specific layer. Accordingly, a method for greatly improving the storability of a latent image only in the objective layer has been keenly demanded.
The present invention provides a method for improving storability of an emulsion in a specific layer and stability of a latent image.
In order to overcome the above-described problems, the present inventors have made extensive investigations on the method for improving storability of an emulsion produced and storability of a latent image, in particular, on the structure of compounds, and as a result, they have found a novel hydroxamic acid-base compound having a specific structure for use in the present invention.
The compound for use in the present invention is found, when added to a silver halide photographic material, able to achieve the objects of the present invention without changing the hue of the dye formed, affecting the dye formation speed of couplers, accelerating the decomposition of the coupler or the dye formed, deteriorating the layer strength or fogging the emulsion.
Out of the compounds for use in the present invention, the compounds represented by formulae (IVA), (IVB), (VA) and (VB) are completely novel compounds which have not known in the past. These compounds are first found to be photographically useful after investigations by the present inventors.